Apparatus and method for preventing moisture condensation

ABSTRACT

An apparatus for preventing moisture condensation includes a fuel cell stack and an enclosure in which the fuel cell stack is disposed. A heater and a temperature sensor are provided in the enclosure. A controller is configured to control the heater to be turned on when an insulation resistance between the fuel cell stack and the enclosure is less than a preset resistance value. The controller controls the heater not to be turned on when a surface temperature of the enclosure measured by the temperature sensor exceeds a preset temperature.

CROSS-REFERENCE(S) TO RELATED APPLICATIONS

The present application claims the benefit of priority to Korean PatentApplication Number 10-2014-0162824 filed on Nov. 20, 2014, the entirecontents of which application are incorporated herein for all purposesby this reference.

TECHNICAL FIELD

The present invention relate to apparatus and method for preventingmoisture condensation which occurs inside a fuel cell stack.

BACKGROUND

A fuel cell system is an electric power generating system for convertingchemical energy of a fuel directly into electrical energy. Generally,the fuel cell system includes a fuel cell stack for generatingelectrical energy. A fuel supply device supplies a fuel (i.e. hydrogen)to the fuel cell stack. An air supply device supplies oxygen in air,which is an oxidizing agent required for an electrochemical reaction, tothe fuel cell stack. A heat and water management device radiatesreaction heat of the fuel cell stack to outside of the system andcontrols an operating temperature of the fuel cell stack. The fuel cellsystem generates electricity as a result of the electrochemical reactionof oxygen included in the air and hydrogen which is the fuel, anddischarges heat and water as by-products of the reaction.

The fuel cell stack applied to a fuel cell vehicle includes a pluralityof unit cells sequentially arranged. Each unit cell includes amembrane-electrode assembly (MEA) disposed at the innermost partthereof. The membrane-electrode assembly includes an electrolytemembrane capable of transporting hydrogen ions (protons), and catalystlayers such as a cathode and an anode, which are coated on both sides ofthe electrolyte membrane such that hydrogen and oxygen can react witheach other. In addition, a gas diffusion layer (GDL) is disposed at anexterior portion of the MEA, i.e. at the exterior portion in which thecathode and the anode are positioned. In addition, a separator, in whichflow fields are formed to supply the fuel and the air to the cathode andthe anode and to discharge water generated by the reaction, ispositioned at an exterior of the GDL. In addition, an end plate ispositioned at both ends of the stack so as to support the stacked cells.

In the stack, hydrogen and oxygen are ionized by chemical reactions byrespective catalyst layers, such that an oxidation reaction generatinghydrogen ions and electrons occurs at an electrode to which the hydrogenis supplied, and a reduction reaction generating water occurs at anelectrode to which oxygen is supplied. Generally, a catalyst including aplatinum catalyst and a cocatalyst, such as Ru, Co, and Cu, with acatalyst support made of a carbon material is usually used as anelectrode catalyst in the fuel cell. That is, hydrogen is supplied tothe anode (referred to as an oxidation electrode), and oxygen, i.e. air,is supplied to the cathode (referred to as a reduction electrode).Accordingly, the hydrogen supplied to the anode is resolved intohydrogen ions (protons) “H+” and electrons “e−” by the catalysts of theelectrode layers configured at both sides of an electrolyte membrane.Then, among the hydrogen ions and electrons, only the hydrogen ions(protons) “H+” are selectively transferred to the cathode through anelectrolyte membrane, which is a positive ion exchange membrane.Simultaneously with this, the electrons “e−” are transferred to thecathode through a gas diffusion layer, which is a conductor, and aseparator. In the cathode, the hydrogen ions supplied through theelectrolyte membrane and the electrons supplied through the separatormeets oxygen in air, which is supplied to the cathode by an air supplydevice, and produces a reaction to generate water. The movement ofhydrogen ions caused at this time causes flow of electrons through anexternal conducting wire to generate current, wherein heat in additionto water is incidentally generated.

In general, the stack is housed by an enclosure in order to physicallyprotect the stack in which a high voltage is generated. However, becauseof moisture introduction through a crevice of the enclosure, moisturecondensation by a temperature difference between inner air and outer airof the enclosure due to an exothermic reaction of the stack, leak ofsome moisture from the stack during operating of the stack, or the like,the components of the stack in the enclosure may be corroded, and aninsulation resistance may be deteriorated.

The information disclosed in this Background section is only forenhancement of understanding of the general background of the disclosureand should not be taken as an acknowledgement or any form of suggestionthat this information forms the prior art already known to a personskilled in the art.

SUMMARY

An aspect of the present inventive concept is directed to apparatus andmethod for preventing moisture condensation inside an enclosure of afuel cell stack by heating the inside of a fuel cell on the basis ofinsulation resistance of a fuel cell vehicle or a difference between asurface temperature of the enclosure and a dew point temperature in theenclosure.

Other objects and advantages of the present invention can be understoodby the following description, and become apparent with reference to theembodiments of the present inventive concept. Also, it is obvious tothose skilled in the art to which the present disclosure pertains thatthe objects and advantages of the present disclosure can be realized bythe means as claimed and combinations thereof.

In accordance with an embodiment of the present inventive concept, anapparatus for preventing moisture condensation includes a fuel cellstack and an enclosure in which the fuel cell stack is disposed. Aheater and a temperature sensor are provided inside the enclosure. Acontroller is configured to control the heater to be turned on when aninsulation resistance between the fuel cell stack and the enclosure isless than a preset resistance value. The controller controls the heaternot to be turned on when a surface temperature of the enclosure measuredby the temperature sensor exceeds a preset temperature.

The controller may be configured to turn on the heater t for apredetermined period of time when the insulation resistance between thefuel cell stack and the enclosure is less than the preset resistancevalue and when the surface temperature of the enclosure is equal to orless than the preset temperature.

The controller may be configured to turn on a warning device when thesurface temperature of the enclosure measured by the temperature sensorexceeds the preset temperature.

The controller may be configured to determine whether an average voltageper cell of the fuel cell stack is greater than or equal to a firstvoltage when a starting-on signal of a vehicle is sensed, and to turn onthe heater when the average voltage per cell of the fuel cell stack isgreater than or equal to the first voltage.

The controller may be configured to turn on the heater when at least oneof a vehicle stop signal and a fuel cell shut-down signal is sensed.

The controller may be configured to turn off the heater when the averagevoltage per cell of the fuel cell stack is less than the first voltageafter the heater is turned on.

In accordance with another embodiment of the present inventive concept,an apparatus for preventing moisture condensation includes a fuel cellstack and an enclosure in which the fuel cell stack is disposed. Aheater and a temperature sensor are provided inside the enclosure. Acontroller is configured to control the heater to be turned on when adew point temperature in the enclosure measured by the temperaturesensor is greater than or equal to a surface temperature of theenclosure. The controller controls the heater not to be turned on whenthe surface temperature of the enclosure exceeds a preset temperature.

The controller may be configured to turn on the heater for apredetermined period of time when the dew point temperature in theenclosure is greater than or equal to the surface temperature of theenclosure and when the surface temperature of the enclosure is equal toor less than the preset temperature.

The controller may be configured to turn on a warning device when thesurface temperature of the enclosure measured by the temperature sensorexceeds the preset temperature.

The controller may be configured to determine whether an average voltageper cell of the fuel cell stack is greater than or equal to a firstvoltage when a starting-on signal of a vehicle is sensed, and to controlthe heater to be turned on when the average voltage per cell of the fuelcell stack is greater than or equal to the first voltage.

The controller may be configured to turn on the heater when at least oneof a vehicle stop signal and a fuel cell shut-down signal is sensed.

The controller may be configured to control the heater to be turned offwhen the average voltage per cell of the fuel cell stack is less thanthe first voltage after the heater is turned on.

In accordance with yet another embodiment of the present inventiveconcept, a method for preventing moisture condensation, comprising stepsof measuring an insulation resistance between a fuel cell stack and anenclosure. Whether the insulation resistance is less than a presetresistance value is determined. Whether a surface temperature of theenclosure measured by a temperature sensor exceeds a preset temperatureis determined. A heater is controlled to be turned on for apredetermined period of time when the surface temperature of theenclosure does not exceed the preset temperature. A warning device iscontrolled to be turned on when the surface temperature of the enclosureexceeds the present temperature.

According to the method for preventing moisture condensation, having theconfiguration as described above, moisture condensation in the enclosurefor the fuel cell stack is suppressed, so that an accident due todeterioration of electrical insulation resistance can be prevented fromoccurring.

In addition, corrosion due to moisture condensation in the enclosure canbe prevented.

In addition, since a high voltage can be rapidly removed during startingor stopping of the stack, deterioration of catalyst due to high-voltageformation is delayed to improve the durability of the stack.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a configuration of an apparatusfor preventing moisture condensation in accordance with an embodiment ofthe present inventive concept.

FIG. 2 is a flowchart illustrating a method for preventing moisturecondensation during traveling of a vehicle in accordance with a firstembodiment of the present inventive concept.

FIG. 3 is a flowchart illustrating a method for preventing moisturecondensation during traveling of a vehicle in accordance with a secondembodiment of the present inventive concept.

FIG. 4 is a flowchart illustrating a method for preventing moisturecondensation during starting of a vehicle in accordance with anembodiment of the present inventive concept.

FIG. 5 is a flowchart illustrating a method for preventing moisturecondensation when starting of a vehicle is interrupted or when a fuelcell shuts down in accordance with an embodiment of the presentinventive concept.

DETAILED DESCRIPTION OF EMBODIMENTS

Apparatus and method for preventing moisture condensation in accordancewith exemplary embodiments of the present inventive concept will bedescribed below in more detail with reference to the accompanyingdrawings. The present inventive concept may, however, be embodied indifferent forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the present disclosure to those skilled in the art.Throughout the disclosure, like reference numerals refer to like partsthroughout the various figures and embodiments of the present inventiveconcept. FIG. 1 is a block diagram illustrating the configuration of anapparatus for preventing moisture condensation in accordance with anembodiment of the present inventive concept.

Referring to FIG. 1, in accordance with a first embodiment of thepresent inventive concept, an apparatus for preventing moisturecondensation may include a fuel cell stack 110 and an enclosure 120containing the fuel cell stack 110. A heater 130 and a temperaturesensor 140 are provided in the enclosure 120. A controller 150 isconfigured to control the heater 130 to be turned on when an insulationresistance between the fuel cell stack 110 and the enclosure 120 is lessthan a preset resistance value. The controller 150 controls the heater130 not to be turned on when a surface temperature of the enclosure 120measured by the temperature sensor 140 exceeds a preset temperature.

In this case, when the insulation resistance between the fuel cell stack110 and the enclosure 120 is less than the preset resistance value andthe surface temperature of the enclosure 120 does not exceed the presettemperature, the controller 150 may control the heater 130 to be turnedon for a predetermined period of time. In addition, when the surfacetemperature of the enclosure 120 measured by the temperature sensor 140exceeds the preset temperature, the controller 150 may control a warningdevice 160 to be turned on.

The enclosure 120 has an air inlet end (not shown) and an outlet end(not shown) for internal air circulation. In this case, the aircirculation through the enclosure 120 may be performed using a pressuredifference between inside and outside, or may be forcibly performed by amotor, an air compressor, or a blower.

The heater 130 is provided on an inner surface of the enclosure 120, andmay include a heating resistor, such as a positive thermal coefficient(PTC) heater.

In accordance with an embodiment of the present inventive concept, thecontroller 150 measures the insulation resistance between the fuel cellstack 110 and the enclosure 120 since the insulation resistance isinfluenced by moisture inside the enclosure 120. When the moisture inthe enclosure is condensed, the insulation resistance is lowered.Therefore, when an insulation resistance equal to or less than apredetermined level is measured during driving of a vehicle, the heater130 is controlled to be turned on for a predetermined period of time,thus preventing and reducing the moisture condensation in the enclosure120 in order to recover a predetermined level of insulation resistance.An insulation resistance regulation prescribes 100 ohms/Vdc in ECE R100,RMVSS 305. Therefore, the preset resistance value in the presentdisclosure may be set to 100 ohms/Vdc+a (wherein “a” represents a marginfor taking safety of electricity into consideration).

When the surface temperature of the enclosure 120 is higher than thepreset temperature, which is a surface limit temperature of theenclosure 120, during heating, the controller 150 may not turn on theheater 130 and may turn on the warning device to notify a driver of adangerous situation because the decrease of the insulation resistance iscaused by not moisture condensation but by another matter to bringanother danger of accident due to overheat. Generally, the presettemperature may be set to less than 100° C.

When sensing a starting-on signal of the vehicle, the controller 150 maydetermine whether or not an average voltage per cell of the fuel cellstack 110 is greater than or equal to a first voltage, and may turn onthe heater 130 when the average voltage per cell of the fuel cell stack110 is greater than or equal to the first voltage.

If a fuel cell vehicle is a parking state for a long period of time, themoisture condensation may occur due to moisture introduced into the fuelcell stack 110 and due to a temperature difference between the stackenclosure 120 and ambient air. In this case, when hydrogen and air aresupplied to drive the vehicle, a stack catalyst and stack durability maydeteriorate due to sharp high-voltage formation.

For this reason, when the average voltage per cell of the fuel cellstack 110 is greater than or equal to the first voltage during startingof a vehicle, the controller 150 determines that the vehicle is in astate in which a high voltage has been formed, and controls the heater130 mounted in the enclosure 120 to be tuned on so as to function as anexothermic body. Accordingly, when the fuel cell vehicle starts, anunnecessary high voltage can be removed to ensure the durability of thefuel cell stack 110, and the temperature of the enclosure 120 canincrease to remove condensed moisture.

In addition, when a vehicle stop signal and/or a shut-down signal forfuel cells are sensed, the controller 150 may turn on the heater 130.This is because a cooling velocity of the surface temperature of theenclosure 120 and a cooling velocity of the ambient air temperature inthe fuel cell stack 110 are different from each other, such that a localdew point in the enclosure 120 is higher than the temperature of theinner surface of the enclosure 120 when the fuel cell vehicle stops orshuts down, thereby causing the moisture condensation. In addition,unreacted hydrogen and air are remained in the fuel cell stack 110, andthus, the high voltage may occur.

Therefore, the controller 150 turns on the heater 130 in the enclosure120 so as to function as an exothermic body, and thus, the high voltagecaused by hydrogen and air in the fuel cell stack 110 can be removed toimprove durability of the fuel cell stack 110. In addition, theexothermic action of the heater 130 dries the inside of the enclosure120, so that a moisture condensation phenomenon can be prevented.

When the average voltage per cell of the fuel cell stack 110 is equal toor less than the first voltage after the heater 130 has been turned on,the controller 150 controls the heater 130 to be turned off.

For example, since a reverse voltage of cells may occur when the averagevoltage per cell of the fuel cell stack 110 is equal to or less than 0.1V, the heater 130 is turned off in order to prevent the reverse voltageof the stacked cells.

In accordance with a second embodiment of the present inventive concept,an apparatus for preventing moisture condensation may include a fuelcell stack 110 and an enclosure 120 containing the fuel cell stack 110therein. A heater 130 and a temperature sensor 140 are provided in theenclosure 120. A controller 150 is configured to control the heater 130to be turned on when a dew point temperature in the enclosure 120measured by the temperature sensor 140 is greater than or equal to asurface temperature of the enclosure 120, or the controller 150 controlsthe heater 130 not to be turned on when the surface temperature of theenclosure 120 exceeds a preset temperature.

When the dew point temperature in the enclosure 120 is greater than orequal to the surface temperature of the enclosure 120, and the surfacetemperature of the enclosure 120 does not exceed the preset temperature,the controller 150 turns on the heater 130 for a predetermined period oftime. In contrast, when the surface temperature of the enclosure 120exceeds a preset temperature, the controller 150 may control a warningdevice 160 to be turned on.

The temperature sensor 140 may be provided to be plural in number.Specifically, the temperature sensor 140 may be provided between thefuel cell stack 110 and the enclosure 120 so as to measure the dew pointtemperature, and may be provided on an inner surface of the enclosure120 so as to measure the surface temperature of the enclosure 120.

According to the second embodiment of the present inventive concept, thecontroller 150 measures the dew point temperature in the enclosure 120and the surface temperature of the enclosure 120 using the temperaturesensor 140, and compares the measured temperatures to determine whethermoisture remained in the enclosure 120 is condensed due to a temperaturedifference between the surface of the enclosure 120 and air surroundingthe enclosure 120. Accordingly, when the dew point temperature in theenclosure 120 is greater than or equal to the surface temperature of theenclosure 120 during driving of the vehicle, the controller 150determines that the moisture in the enclosure 120 is condensed and turnson the heater 130.

Similarly, in the second embodiment of the present inventive concept,when a starting-on signal of the vehicle is sensed, the controller 150determines whether or not an average voltage per cell of the fuel cellstack 110 is greater than or equal to a first voltage and may turn onthe heater 130 when the average voltage per cell of the fuel cell stack110 is greater than or equal to the first voltage. In addition, thecontroller 150 may turn on the heater 130 when a vehicle stop signaland/or a shut-down signal for fuel cells are sensed. The controller 150may turn off the heater 130 when the average voltage per cell of thefuel cell stack 110 is equal to or less than the first voltage after theheater 130 has been turned on.

Hereinafter, a method for preventing moisture condensation in accordancewith exemplary embodiments of the present inventive concept will bedescribed in more detail with reference to the accompanying drawings.FIG. 2 is a flowchart illustrating a method for preventing moisturecondensation during traveling of a vehicle in accordance with a firstembodiment of the present inventive concept. FIG. 3 is a flowchartillustrating a method for preventing moisture condensation in accordancewith a second embodiment of the present inventive concept. FIG. 4 is aflowchart illustrating a method for preventing moisture condensationduring starting of a vehicle in accordance with an embodiment of thepresent inventive concept. FIG. 5 is a flowchart illustrating a methodfor preventing moisture condensation when the starting of a vehicle isinterrupted or when a fuel cell shuts down in accordance with anembodiment of the present inventive concept.

Referring to FIGS. 2 to 5, in accordance with the first embodiment ofthe present inventive concept, a method for preventing moisturecondensation may include measuring an insulation resistance between thefuel cell stack 110 and the enclosure (S200). Whether or not theinsulation resistance is less than a preset resistance value isdetermined (S210). Whether or not a surface temperature of the enclosure120 measured by the temperature sensor 140 exceeds a preset temperatureis determined when the insulation resistance is less than the presetresistance value (S220). The heater 130 is controlled to be turned onfor a predetermined period of time when the surface temperature of theenclosure 120 does not exceed the preset temperature (S230). The warningdevice 160 is controlled to be turned on when the surface temperature ofthe enclosure 120 exceeds the preset temperature (S240).

In addition, in accordance with the second embodiment of the presentinventive concept, a method for preventing moisture condensation mayinclude measuring a dew point temperature in the enclosure 120 and asurface temperature of the enclosure 120 (S300). Whether or not themeasured dew point temperature in the enclosure 120 is greater than orequal to the surface temperature of the enclosure 120 is determined(S310). Whether or not the surface temperature of the enclosure 120measured by the temperature sensor 140 exceeds a preset temperature isdetermined when the dew point temperature in the enclosure 120 isgreater than or equal to the surface temperature of the enclosure 120(S320). The heater 130 is controlled to be turned on for a predeterminedperiod of time when the surface temperature of the enclosure 120 doesnot exceed the preset temperature (S330). The warning device 160 iscontrolled to be turned on when the surface temperature of the enclosure120 exceeds the preset temperature (S340).

When the vehicle starts, the method for preventing moisture condensationmay include sensing a starting-on signal of the vehicle (S400). Whetheror not the average voltage per cell of the fuel cell stack 110 isgreater than a first voltage is determined when the starting-on signalhas been sensed (S410). The heater 130 is controlled to be turned on fora predetermined period of time when the average voltage per cell of thefuel cell stack 110 is greater than the first voltage (S420). Whether ornot the average voltage per cell of the fuel cell stack 110 is equal toor less than a second voltage is determined after the heater 130 hasbeen turned on (S430). The heater 130 is controlled to be turned offwhen the average voltage per cell of the fuel cell stack 110 is equal toor less than the second voltage (S440).

When the vehicle stops or shuts down, the method for preventing moisturecondensation may include sensing a vehicle stop signal or a shut-downsignal (S500). The heater 130 is controlled to be turned on when thestop signal or the shut-down signal has been sensed (S510). Whether ornot the average voltage per cell of the fuel cell stack 110 is equal toor less than a second voltage is determined after the heater 130 hasbeen turned on (S520). The heater 130 is controlled to be turned offwhen the average voltage per cell of the fuel cell stack 110 is equal toor less than the second voltage (S530).

According to the method for preventing moisture condensation asdescribed above, the moisture condensation in the enclosure for the fuelcell stack is suppressed, so that an accident due to deterioration ofelectrical insulation resistance can be prevented from occurring.

In addition, corrosion due to the moisture condensation in the enclosurecan be prevented.

In addition, since a high voltage can be rapidly removed during startingor stopping of the stack, deterioration of catalyst due to high-voltageformation is delayed to improve the durability of the stack.

While the present inventive concept has been described with respect tothe specific embodiments, it will be apparent to those skilled in theart that various changes and modifications may be made without departingfrom the spirit and scope of the disclosure as defined in the followingclaims.

What is claimed is:
 1. An apparatus for preventing moisturecondensation, comprising: a fuel cell stack; an enclosure in which thefuel cell stack is disposed; a heater and a temperature sensor providedinside the enclosure; and a controller configured to control the heaterto be turned on when an insulation resistance between the fuel cellstack and the enclosure is less than a preset resistance value, whereinthe controller controls the heater not to be turned on when a surfacetemperature of the enclosure measured by the temperature sensor exceedsa preset temperature.
 2. The apparatus of claim 1, wherein thecontroller is configured to turn on the heater for a predeterminedperiod of time when the insulation resistance between the fuel cellstack and the enclosure is less than the preset resistance value andwhen the surface temperature of the enclosure is equal to or less thanthe preset temperature.
 3. The apparatus of claim 1, wherein thecontroller is configured to turn on a warning device when the surfacetemperature of the enclosure measured by the temperature sensor exceedsthe preset temperature.
 4. The apparatus of claim 1, wherein thecontroller is configured to determine whether an average voltage percell of the fuel cell stack is greater than or equal to a first voltagewhen a starting-on signal of a vehicle is sensed, and to turn on theheater when the average voltage per cell of the fuel cell stack isgreater than or equal to the first voltage.
 5. The apparatus of claim 1,wherein the controller is configured to turn on the heater when at leastone of a vehicle stop signal and a fuel cell shut-down signal is sensed.6. The apparatus of claim 4, wherein the controller is configured toturn off the heater when the average voltage per cell of the fuel cellstack is less than the first voltage after the heater is turned on. 7.The apparatus of claim 1, wherein the temperature sensor may be providedto be plural in number.
 8. The apparatus of claim 1, wherein the heatermay be provided to be plural in number.
 9. The apparatus of claim 1,wherein the enclosure has an air inlet end an outlet end to circulateair there inside.